Cable/cord Spec for an m81 150w hqi pendant

sayn3ver · 03/26/2017, 05:05 PM

Just curious. It's been a long long time since I've logged in here.

I remember vaguely of a 3-4ft maximum length between a magnetic m81 ballast and the lamp.

More importantly, I need to find or make a pendant cord.
I know the starting voltages of these can be 4000+ volts with miniscule amount of current.

Does anyone know what is the appropriate, safe insulation rating for the conductors?

The ballast I had ordered a long time ago (150w aqua medic reeflex) didn't come with anything. After I called the online retailer than sent me what looked like an old PC power supply cord (300v insulation on a 18/3).

I'm probably over thinking this. I know the 18awg is plenty for the ampacity needed. I feel 300v insulation is not adequate for starting voltage. Or is it such a short duration that any leakage is acceptable?

tkeracer619 · 03/26/2017, 09:06 PM

It's fine to use 300v insulation. MH run on close to wall voltage.

I just use a high quality extension cord. Use a good cord and you can go much further than 4'. All of my ballasts have 10' cords on them.

sayn3ver · 03/26/2017, 09:11 PM

Yes I'm aware the ballast is tapped for a line voltage of 120v.

However the ballast during it's starting circuit will transform that 120v out of the wall and pulse 4000v to get the lamp to strike.

tkeracer619 · 03/26/2017, 09:27 PM

It isn't an issue. I've never seen any halide come with a 4000v cable

I've installed many HPS ballasts as well and all of them burst 2500-4000v. They all used 300v wiring. 150w MH act the same way. Most 250w halides don't.

biglurr54 · 03/28/2017, 06:21 PM

I used 14 thhn wire. It's about 6 1/2 feet long. No shocks yet and the light works great. Have about 5 years on the ballast and wiring.

Sent from my SM-G928V using Tapatalk

03/26/2017, 05:05 PM	#1
sayn3ver Registered Member Join Date: Nov 2006 Location: NJ 08109 (right outside philly) Posts: 407	Cable/cord Spec for an m81 150w hqi pendant Just curious. It's been a long long time since I've logged in here. I remember vaguely of a 3-4ft maximum length between a magnetic m81 ballast and the lamp. More importantly, I need to find or make a pendant cord. I know the starting voltages of these can be 4000+ volts with miniscule amount of current. Does anyone know what is the appropriate, safe insulation rating for the conductors? The ballast I had ordered a long time ago (150w aqua medic reeflex) didn't come with anything. After I called the online retailer than sent me what looked like an old PC power supply cord (300v insulation on a 18/3). I'm probably over thinking this. I know the 18awg is plenty for the ampacity needed. I feel 300v insulation is not adequate for starting voltage. Or is it such a short duration that any leakage is acceptable? __________________ never say never Current Tank Info: AP24 in the works

03/26/2017, 09:06 PM	#2
tkeracer619 Registered Member Join Date: Jan 2006 Location: Westminster, CO Posts: 17,289	It's fine to use 300v insulation. MH run on close to wall voltage. I just use a high quality extension cord. Use a good cord and you can go much further than 4'. All of my ballasts have 10' cords on them. __________________ Hobby Experience: 9200ish gallons, 26 skimmers, and a handful of Kent Scrapers. Current Tank: Vortech Powered 600G SPS Tank w/ 100gal frag tank & 100g Sump. RK2-RK10 Skimmer. ReefAngel. Radium 20k.

03/26/2017, 09:11 PM	#3
sayn3ver Registered Member Join Date: Nov 2006 Location: NJ 08109 (right outside philly) Posts: 407	Yes I'm aware the ballast is tapped for a line voltage of 120v. However the ballast during it's starting circuit will transform that 120v out of the wall and pulse 4000v to get the lamp to strike. __________________ never say never Current Tank Info: AP24 in the works

03/26/2017, 09:27 PM	#4
tkeracer619 Registered Member Join Date: Jan 2006 Location: Westminster, CO Posts: 17,289	It isn't an issue. I've never seen any halide come with a 4000v cable I've installed many HPS ballasts as well and all of them burst 2500-4000v. They all used 300v wiring. 150w MH act the same way. Most 250w halides don't. __________________ Hobby Experience: 9200ish gallons, 26 skimmers, and a handful of Kent Scrapers. Current Tank: Vortech Powered 600G SPS Tank w/ 100gal frag tank & 100g Sump. RK2-RK10 Skimmer. ReefAngel. Radium 20k.

03/28/2017, 06:21 PM	#5
biglurr54 Registered Member Join Date: Dec 2005 Location: Averill Park NY Posts: 406	I used 14 thhn wire. It's about 6 1/2 feet long. No shocks yet and the light works great. Have about 5 years on the ballast and wiring. Sent from my SM-G928V using Tapatalk